GPT-5.5

openai/gpt-5.5

OpenAI: GPT-5.5 on Sylphx Models · 400K of context. One Responses contract, with list prices published per million tokens.

Released: Apr 23, 2026 · 151 days old
Provider: OpenAI
Context: 400,000 tokens

Open in the playground See a request sample Read the docs

Input $5.00 / MOutput $30.00 / MCached input $0.5 / MFull rate sheet

Context window400,000tokens per request

Max output128,000tokens per response

Input$5.00 / Mper million tokens

Output$30.00 / Mper million tokens

Requests · 7d0metered on Responses

Avg TPM · 7d00 tokens

Pricing

USD per million tokens

Input: $5.00
Output: $30.00
Cached input: $0.5

$11.25 for 750,000 input and 250,000 output tokens.

Assumption: one batch of 750,000 input plus 250,000 output tokens at the published list prices — recompute for your own mix. Blended $11.25 per million at a 3:1 mix.

Chat replies · 3:1 input:output: $11.25 / M
Long documents · 9:1 input:output: $7.50 / M
Heavy output · 1:1 input:output: $17.50 / M
Cache write: Not published
Currency and unit: USD / million tokens

Cached input reads cost 90% less than fresh input tokens.

Full rate sheet and billing rules.

Specification

Context window: 400,000 tokens
Max output: 128,000 tokens
Input modalities: Not published
Output modalities: Not published
Family: GPT
Version: v5.5
Provider: OpenAI
Released: Apr 23, 2026 · 151 days old
Model id: openai/gpt-5.5

Data posture

Standard

Prompts and outputs sent to this model are not used to train models.

Training on what you send: No
Zero Data Retention: Available

Traffic

Daily traffic the platform metered on Responses for this exact model id. Totals are the window they name; a day with no traffic is zero, not missing.

Requests · last 7 days: 0
Tokens · last 7 days: 0
Average TPM · last 7 days: 0
Series total · 14d: Not published

No 14-day series published

The catalog does not publish a daily series for this model yet. The seven-day totals above still come from the catalog.

POST https://api.models.sylphx.ai/v1/responses

curl https://api.models.sylphx.ai/v1/responses \
  -H "Authorization: Bearer $SYLPHX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-5.5",
    "input": "Summarise this incident report in three bullets.",
    "stream": false
  }'

How to call it

Send the official Responses document to the base URL above with your organization key and this exact model id. Streaming arrives as ordered events with one terminal event.

Retries: send an Idempotency-Key and a retry replays the original response instead of billing twice.
Errors: typed envelopes tell you whether to retry, wait, or fix the request.
Keys: mint and revoke organization keys from the console.

Quickstart Responses API Errors and retries

Related models

Derived from this catalog: same provider first, then the same family, then the nearest neighbours by input price and context window.

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Independent evaluation

We do not publish benchmark scores for this model — we have not verified any. These external leaderboards run their own tests, so check them against your own workload.

Not our numbers

No traffic reportedNo traffic metered on openai/gpt-5.5 over the last seven daysEvery OpenAI model →